In the present study, the effects of different doses of nicotine on immobility time in mice were tested. Intraperitioneal administration of low doses of nicotine (0.025 mg/kg) decreased, but higher doses (0.8 and 1 mg/kg) increased immobility time. The anti-immobility response induced by low doses of nicotine was inhibited by high doses of the D2 receptor antagonist sulpiride, the central nicotinic receptor antagonist mecamylamine, reserpine and propranolol. The D1 receptor antagonist SCH 23390, the peripheral D2 receptor antagonist domperidone, hexamethonium, phenoxybenzamine and atropine did not alter nicotine effect. It can be concluded that the anti-immobility effect induced by low doses of nicotine is mediated by D2 dopamine receptor mechanism and possibly through a central nicotinic receptor stimulation.
